Legal Question in Wills and Trusts in California

You are correct about the meaning of "executor," but a living will would normally name an executor since a will needs an executor once the testator dies. That said, a "living will" is not really a legal term, but most commonly is used to refer to what really is an intervivos trust. Given that she needs permission from the "executor" for expenses, it sounds like the person is a trustee of a trust set up by the man. If that is the case, getting married would not alter the financial situation, unless the man also revoked the trust (assuming it is revocable as most intervivos trusts are, but not all). The fact that the man has dementia does not automatically make him incapable of marrying or making his own financial decisions. It would depend on the degree and nature of the dementia. However, if it is serious and advanced to the point that he is not mentally competent to make personal and financial decisions and fully understand the consequences of such actions, the marriage and any other things he might do would be void. So you are correct that she is probably making a mess for herself if she marries him thinking it will solve her issues with the executor/trustee.